use crate::{HttpClient, HttpRequestExt};
use anyhow::{Context as _, Result, anyhow, bail};
use futures::AsyncReadExt;
use http::Request;
use serde::Deserialize;
use std::sync::Arc;
use url::Url;

const GITHUB_API_URL: &str = "https://api.github.com";

pub struct GitHubLspBinaryVersion {
    pub name: String,
    pub url: String,
    pub digest: Option<String>,
}

#[derive(Deserialize, Debug)]
pub struct GithubRelease {
    pub tag_name: String,
    #[serde(rename = "prerelease")]
    pub pre_release: bool,
    pub assets: Vec<GithubReleaseAsset>,
    pub tarball_url: String,
    pub zipball_url: String,
}

#[derive(Deserialize, Debug)]
pub struct GithubReleaseAsset {
    pub name: String,
    pub browser_download_url: String,
    pub digest: Option<String>,
}

pub async fn latest_github_release(
    repo_name_with_owner: &str,
    require_assets: bool,
    pre_release: bool,
    http: Arc<dyn HttpClient>,
) -> anyhow::Result<GithubRelease> {
    let url = format!("{GITHUB_API_URL}/repos/{repo_name_with_owner}/releases");

    let request = Request::get(&url)
        .follow_redirects(crate::RedirectPolicy::FollowAll)
        .when_some(std::env::var("GITHUB_TOKEN").ok(), |builder, token| {
            builder.header("Authorization", format!("Bearer {}", token))
        })
        .body(Default::default())?;

    let mut response = http
        .send(request)
        .await
        .context("error fetching latest release")?;

    let mut body = Vec::new();
    response
        .body_mut()
        .read_to_end(&mut body)
        .await
        .context("error reading latest release")?;

    if response.status().is_client_error() {
        let text = String::from_utf8_lossy(body.as_slice());
        bail!(
            "status error {}, response: {text:?}",
            response.status().as_u16()
        );
    }

    let releases = match serde_json::from_slice::<Vec<GithubRelease>>(body.as_slice()) {
        Ok(releases) => releases,

        Err(err) => {
            log::error!("Error deserializing: {err:?}");
            log::error!(
                "GitHub API response text: {:?}",
                String::from_utf8_lossy(body.as_slice())
            );
            anyhow::bail!("error deserializing latest release: {err:?}");
        }
    };

    let mut release = releases
        .into_iter()
        .filter(|release| !require_assets || !release.assets.is_empty())
        .find(|release| release.pre_release == pre_release)
        .context("finding a prerelease")?;
    release.assets.iter_mut().for_each(|asset| {
        if let Some(digest) = &mut asset.digest
            && let Some(stripped) = digest.strip_prefix("sha256:")
        {
            *digest = stripped.to_owned();
        }
    });
    Ok(release)
}

pub async fn get_release_by_tag_name(
    repo_name_with_owner: &str,
    tag: &str,
    http: Arc<dyn HttpClient>,
) -> anyhow::Result<GithubRelease> {
    let url = format!("{GITHUB_API_URL}/repos/{repo_name_with_owner}/releases/tags/{tag}");

    let request = Request::get(&url)
        .follow_redirects(crate::RedirectPolicy::FollowAll)
        .when_some(std::env::var("GITHUB_TOKEN").ok(), |builder, token| {
            builder.header("Authorization", format!("Bearer {}", token))
        })
        .body(Default::default())?;

    let mut response = http
        .send(request)
        .await
        .context("error fetching latest release")?;

    let mut body = Vec::new();
    let status = response.status();
    response
        .body_mut()
        .read_to_end(&mut body)
        .await
        .context("error reading latest release")?;

    if status.is_client_error() {
        let text = String::from_utf8_lossy(body.as_slice());
        bail!(
            "status error {}, response: {text:?}",
            response.status().as_u16()
        );
    }

    let release = serde_json::from_slice::<GithubRelease>(body.as_slice()).map_err(|err| {
        log::error!("Error deserializing: {err:?}");
        log::error!(
            "GitHub API response text: {:?}",
            String::from_utf8_lossy(body.as_slice())
        );
        anyhow!("error deserializing GitHub release: {err:?}")
    })?;

    Ok(release)
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum AssetKind {
    TarGz,
    Gz,
    Zip,
}

pub fn build_asset_url(repo_name_with_owner: &str, tag: &str, kind: AssetKind) -> Result<String> {
    let mut url = Url::parse(&format!(
        "https://github.com/{repo_name_with_owner}/archive/refs/tags",
    ))?;
    // We're pushing this here, because tags may contain `/` and other characters
    // that need to be escaped.
    let asset_filename = format!(
        "{tag}.{extension}",
        extension = match kind {
            AssetKind::TarGz => "tar.gz",
            AssetKind::Gz => "gz",
            AssetKind::Zip => "zip",
        }
    );
    url.path_segments_mut()
        .map_err(|()| anyhow!("cannot modify url path segments"))?
        .push(&asset_filename);
    Ok(url.to_string())
}

#[cfg(test)]
mod tests {
    use crate::github::{AssetKind, build_asset_url};

    #[test]
    fn test_build_asset_url() {
        let tag = "release/2.3.5";
        let repo_name_with_owner = "microsoft/vscode-eslint";

        let tarball = build_asset_url(repo_name_with_owner, tag, AssetKind::TarGz).unwrap();
        assert_eq!(
            tarball,
            "https://github.com/microsoft/vscode-eslint/archive/refs/tags/release%2F2.3.5.tar.gz"
        );

        let zip = build_asset_url(repo_name_with_owner, tag, AssetKind::Zip).unwrap();
        assert_eq!(
            zip,
            "https://github.com/microsoft/vscode-eslint/archive/refs/tags/release%2F2.3.5.zip"
        );
    }
}
